31 terms

Chapter 5 terms Biology

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active site
the place on an enzyme where the substrate is broken down
active transport
the movement of molecules across a membrane from a region of their lower concentration to a region of their higher concentration—against the concentration gradient. requires cellular energy
adenosine triphosphate (ATP)
the organic energy molecule that is main energy source. releases energy when its phosphate bonds are hydrolyzed.
bioluminescence
the biochemical emission of light by living organisms
cellular respiration
the energy releasing chemical breakdown of food molecules, such as glucose, and the storage of potential energy in a form that cells can use to perform work;
chemical energy
energy stored in the form of a potential chemical reaction
concentration gradient
the difference in concentration of a substance in different areas
diffusion
the process by which the random movement of particles results in the net movement of a substance down its concentration gradient
Endocytosis
the process by which a cells brings substances into itself in membrane enclosed vesicles
energy of activation (EA)
the amount of energy needed to start a chemical reaction
Energy
the ability to cause change in surroundings/do work
Enzyme
a protein with a specific shape that allows it to catalyze the breaking down of complex molecules
exocytosis
the process by which a cells exports substances from itself in membrane enclosed vesicles
facilitated diffusion
diffusion of a substance across the membrane through channels
Heat
the transfer of thermal energy
hypertonic solution
a solution that has a higher concentration of solutes
hypotonic solution
a solution that has a lower concentration of solutes
isotonic solution
a solution that has the same concentration of solutes
kinetic energy
energy of motion
metabolism
the totality of an organism's chemical reactions
osmoregulation
the homeostatic maintenance of solute concentrations and water balance by a cell or organism
osmosis
the diffusion of water across a selectively permeable membrane
passive transport
the diffusion of a substance across a biological membrane, with no expenditure of energy
phagocytosis
cellular "eating"; a type of endocytosis in which a cell engulfs macromolecules, other cells, or particles into its cytoplasm
phosphorylation
the transfer of a phosphate group, usually from ATP, to a molecule. Nearly all cellular work depends on ATP energizing other molecules by phosphorylation.
pinocytosis
cellular "drinking"; a type of endocytosis in which a cell engulfs liquids into its cytoplasm
potential energy
energy that is stored by the unstable arrangement of matter
receptor mediated endocytosis
the movement of specific molecules into a cell by the infolding of vesicles containing proteins with receptor sites specific to the molecules being taken in
selective permeability
the ability of a membrane to allow certain substances to pass through while preventing others
substrate
the substance on which a specific enzyme acts
tonicity
the ability of a solution surrounding a cell to cause that cell to gain or lose water